Electrically luminescent device

ABSTRACT

An electrically luminescent device having an electroluminescent element and associated power supply electrodes, at least one of the electrodes being in the form of a gapped structure consisting of fine metal wires which are arranged in parallel with each other or in a reticulate fashion. In the device, mere coating or placement of a low-resistance substance such as water, an alcohol, a conductive paint or an evaporated metal film on the gap portion of the gapped electrode in such a manner as to conform with the shape of a character or pattern to be displayed can easily attain the luminous display of the character or pattern.

United States Patent 1 Suzuki et al.

[451 June 19,1973

1 1 ELECTRICALLY LUMINESCENT DEVICE [73] Assignee: Matsushita ElectricIndustrial Co.,

Ltd., Osaka, Japan [22] Filed: Jan. 2, 1970 [21] Appl. No.: 482

Related U.S. Application Data [63] Continuation of Ser. No. 677,138,Oct. 23, 1967,

abandoned. I

[30] Foreign Application Priority Data om. 27, 1966 Japan 41 71302 Oct.27, 1966 Japan 41171304 Oct. 27, 1966 Japan 41/71305 Oct. 27, 1966 Japan41/71306 Oct. 27, 1966 Japan... 41/71307 Oct. 27, 1966 Japan 41/71308[52] U.S. Cl 317/234 R, 313/108 A, 317/235 N [51] Int. Cl. H011 15/00[58] Field of Search 317/235 N; 313/108,

[5 6] References Cited UNITED STATES PATENTS 3,211,663 10/1965 Bueleza252/301.l 3,167,677 1/1965 Fremonth 313/108 3,048,732 8/1962 Lehmann313/108 3,152,994 10/1964 Thornton..... 252/3016 3,252,845 5/1966Schindler..... 156/67 3,290,537 12/1966 Logan 313/108 3,348,056 10/1967Kobashi 250/213 Primary ExaminerMartin H. Edlow Att0rneyStevens, Davis,Miller & Mosher [57] ABSTRACT An electrically luminescent device havingan electroluminescent element and associated power supply electrodes, atleast one of the electrodes being in the form of a gapped structureconsisting of fine metal wires which are arranged in parallel with eachother or in a reticulate fashion. in the device, mere coating orplacement of a low-resistance substance such as water, an alcohol, aconductive paint or an evaporated metal film on the gap portion of' thegapped electrode in such a manner as to conform with the shape of acharacter or pattern to be displayed can easily attain the luminousdisplay of the character or pattern.

7 Claims, 8 Drawing Figures Patented June 19, 1973 3,740,616

3 Shoots-Shoot 1 Patented June 19, 1973 I 3,740,616

3 Shoots-Shoot 5 l ELECTRICALLY LUMINESCENT DEVICE This application is acontinuation of Ser. No. 677,138 filed Oct. 23, 1967 (now abandoned).

This invention relates to an electrically luminescent device employingtherein an electrically luminescent element such as anelectroluminescent element which luminesces depending on the strength ofan electric field applied thereto, and contemplates to provide anelectrically luminescent device of the above kind whose luminouslydisplaying section can easily be controlled for the display of thedesired character or pattern.

Prior electrically luminescent devices employing thereinelectroluminescent elements which are adapted to give a luminous displayof a character or pattern have such a structure that at least one of theelectrodes is shaped to the form of the character or pattern to bedisplayed and power is supplied to this electrode by some suitable meansto effect the display of the desired character or pattern. In view ofsuch a structure, many electrodes must be provided and individuallyconnected by way of feeder wires to a power supply in order to displayacomplex character or pattern consisting of many elements which areisolated from one another, with the result that the structure of theelectrically luminescent device becomes very complex and an extremedifficulty is involved in the manufacture of the electrodes representingthe character or pattern to be displayed. 7

It is therefore the primary object of the present invention to provide anovel electrically luminescent device having a power supply electrodewhich is in the form of a plural-gapped electrode consisting of veryfine metal wires arranged in a parallel or reticulate relation forthereby enabling to display a character or pattern of whatever shape.

The above and other objects, advantages and features of the presentinvention will become apparent from the following description withreference to the accompanying drawings.

In'the drawings:

FIG. 1 is a schematic sectional view of an electrically luminescentdevice embodying the present invention;

FIGS. 2, 3, 4, 5 and 6 are schematic sectional views of otherembodiments according to the present invention;

FIG. 7 is a diagrammatic view showing the manner of operation of thedevice shown in FIG. 6; and

FIG. 8 is a'schematic sectional view of another embodiment according tothe present invention.

FIG. 1 shows the structure of an embodiment of the electricallyluminescent device according to the present invention and a power supplysystem therefor. The electrically luminescent device shown in FIG. 1comprises a support base 1, a planar electrode 2, an electricallyluminescent layer 3 which luminesces depending on the strength of anelectric field applied thereto, a dielectric layer 4 of a material suchas plastics having a high resistivity, and a plural-'gapped electrode 5consisting of plural fine wire electrodes which are arranged in parallelwith each other. In the device, a voltage is applied across theelectrodes 5 and 2 from a power supply8 by way of lead wires 6 and 7.

The support base I may be made of a transparent material such as glassor of an opaque material such as bakelite. The term transparent" usedherein is intended to denote the fact that a transparent" material orlayer permits transmission therethrough of the luminescence emitted fromthe electrically luminescent layer 3.

The conductive electrode 2 is bonded or otherwise fixed to the supportbase 1, but where the support base 1 is made of, for example,transparent glass, the conductive electrode 2 must also be transparentand may be made from a conductive transparent metal oxide such as tinoxide. In case the support base 1 of opaque nature is employed, theelectrode 2 need not be transparent and may be an opaque metal film suchas an evaporated aluminum film.

When the device is intended to operate with an alternating current, theelectrically luminescent layer 3 may be made by preparing a compositionconsisting of, for example, zinc sulfide powder activated with copperand aluminum and a plastic binder such as urea resin and laminating thecomposition to a thickness of, for example, 50 microns. The electricallyluminescent layer 3 having the above composition has such a propertythat it emits a green luminescence when an ac electric field is appliedthereto, and its luminous output varies nonlinearly in proportion to anyincrease or decrease in the strength of the ac. electric field.

The dielectric layer 4 having a high resistivity may, for example, be alayer of an epoxy resin. At least either the layer 4 or the support base1 should be transparent with respect to the luminescence emitted fromthe electrically luminescent layer 3. Accordingly, the highly resistivedielectric layer 4 may be either opaque or transparent when the supportbase 1 is transparent. When both the support base 1 and the highlyresistive dielectric layer 4 are transparent, the luminescence emittedfrom the electrically luminescent layer 3 can be observed through thebase 1 and the dielectric layer 4. When the support base 1 is opaque,the highly resistive dielectric layer 4 must be transparent with respectto the luminescence emitted from the electrically luminescent layer 3.The highly resistive dielectric layer 4 may preferably be such that itsspecific resistance and- /or its surface insulation resistivity isgreatly varied by moisture or water. For example, the dielectric layer 4may be molded to a laminar form having a thickness of about 10 micronsfrom a composition consisting of an epoxy resin made by Union CarbideCo. under the trade name ERL-2774 and a suitable amount of a plasticizermade by the same company under the trade name ZZL-O845.

The electrode 5 may consist of tungsten wires having a diameter of, forexample, 10 microns which are arranged in an equally spaced parallelrelation with a spacing in the order to microns therebetween. Thespacing between the adjacent wires need be narrowed as much as possiblein order to display a very fine and complex character or pattern, butthe spacing may desirably be larger than the total thickness of thelayers lying between the electrodes 5 and 2 in order that theluminescence emitted without giving any display, that is, the darkluminescence may not become so intense. Further, the diameter of themetal wire may preferably be as small as possible in order to avoid theundesirable high intensity of the luminescence emitted in the absence ofany display, that is, the dark luminescence.

The plural-gapped electrode 5 may consist of a plurality of strip-likeevaporated films of a metal such as aluminum which are evaporated ontothe highly resistive dielectric layer 4. In another form of theelectrode 5, the plural-gapped electrode may have a reticulatestructure. The reticulate electrode may be obtained by arranging aplurality of fine metal wires in a perpendicular relation with oneanother, or by employing a metal network, or by evaporating a pluralityof metal films in a reticulate fashion.

The electrode 5 may desirably be disposed in such a way that it ispartly projected above the surface of the highly resistive dielectriclayer 4 in order that it can satisfactorily serve as a power supplyelectrode, but the electrode 5 may not necessarily be projected abovethe surface of the dielectric layer 4 in case the specific resistance ofthe highly resistive dielectric layer 4 itself is greatly varied by thepresence of moisture or the like. In the latter case too, the electrode5 can properly act as a power supply electrode.

The operating principle of the present embodiment will be described indetail with reference to FIG. 1. A voltage is applied across theelectrodes 2 and 5 from the power supply'8 by way of the lead wires 6and 7. In this case, those portions of the electrically luminescentlayer 3 underlying the wires of the pIural-gapped electrode 5 may emitsome luminescence due to the fact that an electric field is appliedthereto. However, in view of the fact that the electrode wires have thediameter in the order of 10 microns and are spaced from each other bythe distance in the order of 100 microns and the total thickness of theelectrically luminescent layer 3 and the highly resistive dielectriclayer 4 is in the order of 60 microns as described previously, theluminescence emitted from the electricallyluminescent layer 3 as a wholeis such that it is very weak or substantially negligible, and as amatter of fact, so weak that it can be hardly detected. Thus, theelectrode 5 is only operative to merely supply the power to theelectrically luminescent layer 3 and does not energize directly theelectrically luminescent layer 3.

Under the state in which the applied voltage is suitably adjusted sothat the electrically luminescent layer 3 can hardly emit theluminescence in the manner as described above, a liquid such as waterwhich has a low resistance may be dropped onto the surface of the highlyresistive dielectric layer 4. When at least a portion of the liquidcontacts a wire of the electrode 5, the surface potential of thedielectric layer 4 about the particular wire of the electrode 5 makes anincrease due to the fact that the surface conductivity along the surfaceof the highly resistive dielectric layer 4 between ..the wires of theelectrode 5 makes an increase by the presence of the liquid. As -aresult, the internal portion of the electrically luminescent layer -3which corresponds to the position of existence of the liquid issubjected to the action of an increased electric field and thus emits astronger luminescence. Thus, the portion wetted with the liquid, such aswater, which has a low resistance, that is, the portion of a characteror pattern depicted by the liquid is made to intensely luminesce.

Moisture acts in the same manner as in application of a substance suchas water which has a low insulation resistance. The presence of localmoisture also acts to cause a remarkable reduction in the insulationresistance at the surface of the highly resistive dielectric layer 4 sothat, when at least a portion of the surface having its insulationresistance lowered by the presence 7 of moisture is in contact with awire of the electrode 5,

that portion of the electrically luminescent layer 3 corresponding tothe portion of local existence of the moisture luminesces as in the caseof wetting the layer 4 with water which has a low insulation resistance.When it is desired to cease the luminescence emitted from the portionwetted with the liquid such as water, theliquid may merely be wiped awayby a piece of cloth or the like to restore the surface of the highlyresistive dielectric layer 4 to its non-wetted state, which ceases theluminescence of the electrically luminescent layer 3.

In FIG. 2, there is shown the structure of another embodiment of theelectrically luminescent device according to the present invention and apower supply system therefor. I

The embodiment shown in FIG. 2 is generally similar to that shown inFIG. 1, but is featured by the provision of a electrically insulatinglayer 9 such as a polyester film on an electrically luminescent layer 3in order to give an increased insulation thereto. The provision of suchlayer 9 is effective because those portions of the electricallyluminescent layer 3 contacted by electrode wires of an electrode 5 aregenerally liable to cause a dielectric breakdown. The insulation layer 9may be prepared by laminating a composition consisting of powdery bariumtitanate and a plastic binder. In this case, the dielectric layer 9' iswhite in color and therefore reflects the luminescence emitted from theelectri cally luminescent layer 3, thus intensifying the light outputand giving an increased effectiveness.

In FIG. 3, there is shown the structure of a further embodiment of theelectrically luminescent device according to the present invention and apower supply system therefor.

The embodiment shown in FIG. 3 is generally similar to that shown inFIG. 1, but is featured by the provision of a direct current powersupply 8. The direct current power supply 8 may be employed to cooperatewith an electrically luminescent layer 3 when such layer is formed froma luminescent material such as cadmium sulfide or silicon carbide whichluminesces when energized by a direct current, or such layer is made byevaporating zinc sulfide powder activated with copper or manganese. in athin film form. In this case, the resistivity of a highly resistivedielectric layer 4 must be slightly reduced in order to allow forpassage there through of the direct current.

In FIG. 4, there is shown the structure of another embodiment of theelectrically luminescent device according to the present invention and apower supply system therefor.

The embodiment shown in FIG. 4 is featured by the provision of a pair ofplural-gapped electrodes 2 and 5 each consisting of plural electrodewires, a support base 1 which supports a pair of dielectric layers 4' onopposite faces thereof, and a pair of electrically luminescent layers 3and 10 interposed between the base 1 and the layers 4, so that acharacter or pattern can be displayed on the opposite faces of thelayers 4 contacted by the electrodes 2 and 5. In this embodiment, theelectrically luminescent layer 3 is principally operative to display acharacter or pattern on the surface including the-electrode 2, while theelectrically luminescent layer 10 is principally operative to display acharacter or pattern on the surface including the electrode 5. Acharacter or pattern displayed on the surface including the electrode 2can be made quite independent of a character or pattern displayed on thesurface including the electrode 5 when an opaque dielectric material isemployed to form the support base 1.

Further, characters or patterns having different colors may be displayedwhen the electrically luminescent layers 3 and are so selected as toemit the luminescence of different colors. Although the electrodes 2 and5 are shown herein as disposed in a registered relation, it will easilybe understoodthat the electrode 2 may be disposed to overlie the gapportions of the electrode 5, or the electrodes 2 and 5 may be disposedto intersect in a perpendicular relation or in an angular relation witheach other.

In FIG. 5, there is shown a further embodiment of the electricallyluminescent device according to the present invention and a power supplysystem therefor.

The embodiment shown in FIG. 5 is similar to that shown in FIG. 4 in theprovision of a pair of pluralgapped electrodes 2 and 5, but is differentin that a single electrically luminescent layer 3 is provided in lieu ofthe two layers in the embodiment shown in FIG. 4. In this embodiment,when the voltage at a power supply 8 may be suitably adjusted,characters or patterns depicted on the surfaces including the electrodes2 and 5 may luminesce solely at their intersections to thereby give adisplay of points in the two-dimensional display device. In FIG. 6,there is shown the structure of another embodiment of the electricallyluminescent device according to the present invention and a power supplysystem therefor.

The embodiment shown in FIG. 6 is featured by the fact that threeelectrodes, two of which are pluralgapped electrodes, are connected withtwo power supplies, and two electrically luminescent elements emittingthe luminescence of different colors are employed so that a portionhaving thereon a conductive substance depicted in the shape to conformwith a character or pattern to be displayed luminesces with a colordifferent from a color with which the remaining portion luminesces.

Referring to FIG. 6, the electrically luminescent device comprises atransparent support base 11 of glass or like material, a transparentelectrode 12 of a metal oxide such as tin oxide, a transparent impedancelayer 13 of a material such as plastics, electrically luminescent layers14 and 16, a plural-gapped electrode 15 interposed between theelectrically luminescent layers 14 and 16, a electrically insulatinglayer 17 in the form of, for example, a polyester film, a dielectriclayer 18 having a high resistivity made from a material such as an epoxyresin, a plural-gapped electrode 19, and a.c. power supplies 23 and 24for applying voltages at the same frequency across the electrodes 15 and19 by way of lead wires 20 and 21 and across the electrodes 15 and 12 byway of lead wires 20 and 22, respectively.

The impedance layer 13 may not necessarily be transparent when it ispossible to observe the luminescence of the electrically luminescentlayers 14 and 16 from the side of the electrode 19. The electricallyluminescent layers 14 and 16 give luminescences of different colors andmay, for example, be a green-emitting electroluminescent element in theform of ZnS: Cu,Al and an orange-emitting electroluminescent element inthe form of ZnCdS: Ag, respectively. In this case, it is desirable thatthe electrically luminescent element layer emitting the. luminescence ofa shorter wavelength is disposed nearer to the surface through which theluminescence is to be observed. The plural-gapped electrode 15 in thisembodiment consists of a plurality of fine wires of a metal such astungsten having a diameter in the order of 20 microns which areparallelly disposed with a spacing in the order of 200 to 300 microns.The electrode 15 may be a reticulate electrode which is made by knittinga plurality of metal wires in a reticulate fashion. The plural-gappedelectrode 19 in this embodiment consists of plural fine wires of a metalsuch as tungsten having a diameter in the order of 20 microns which areparallelly disposed with a spacing in the order of microns.

The operating principle of the device shown in FIG. 6 will be describedwith reference to FIG. 7. In FIG. 7, voltages V, and V at the respectivepower supplies 23 and 24, and currents I and I associated with thesevoltages respectively are shown in their ideal situation in which theyhave an antiphase relation with each other. As will be apparent fromFIG. 7, the currents l,

and I operate in a differential fashion. In a dark state in which anycharacter or pattern is not displayed due to mere application of thevoltages, the current flowing in the vicinity of the electrode 15 isgiven by /l, l When the voltage V is so selected as to be slightlyhigher than V, in order to have a relation /I /l,/, the luminescence isprimarily governed by the current I flowing between the electrodes 15and 12, and the electrically luminescent layer 14 luminesces due to thehigh density of the current flowing through the electrically luminescentlayer 14 which is nearer to the electrode 12. On the other hand, due tothe small density of the current flowing through the electricallyluminescent layer 16 which is nearer to the electrode 19, theelectrically luminescent layer 16 hardly luminesces, and therefore thecolor of luminescence of the device as a whole is represented by thecolor of luminescence of the electrically luminescent layer 14.

Suppose now that a droplet 25 ofa liquid, such as water, having a lowinsulation resistance is placed on the surface of the highly resistivedielectric layer 18, and at least a portion of the droplet 25 contactsthe electrode wire of the electrode 19. Then, due to the fact that thesurface conductivity along the surface portion of the highly resistivedielectric layer 18 between the electrode wires 19 is increased, thesurface potential about the particular wire of the electrode 19increases so that the density of the current flowing in the vicinity ofthe portion underlying the conductive liquid droplet 25 working as anelectrode makes a corresponding increase as shown by I,'. Since theconductive liquid droplet 25 is placed in a shape to conform with theshape of a character or pattern to be displayed, the resultant increasein the density of the current flowing through the portion of theelectrically luminescent layer 16 which underlies the liquid droplet 25causes the electrically luminescent layer 16 to strongly luminesce atthat portion. On the other hand, the current I, flowing into theelectrically luminescent layer 14 disposed nearer to the electrode 12 isoperative to cancel the current to thereby weaken the luminescence ofthe electrically luminescent layer 14 having luminesced in its darkstate by being energized by the current I Therefore, the portionrepresenting the character or pattern is intensely illuminated by theluminescence of the electrically luminescent layer 16, while theremaining or non-depicted portion is illuminated by the weakluminescence of the electrically luminescent layer 14.

In case the voltage V, is solely applied, the luminescence occurssubstantially solely in the electrically luminescent layer 16 due toless flow of the current I, through the electrically luminescent layer14. In such a case, therefore, the portion representing a character orpattern is illuminated by the luminescence of the electricallyluminescent layer 16, while the remaining or non-depicted portion issubstantially free from any luminescence.

Further, by suitably selecting the magnitude of the voltage V relativeto the voltage V, in such a manner that the current I exactly cancelsthe dark luminescence caused by the current I, produced by the voltage Vthe image of a character or pattern produced by the current I can bedisplayed with a very high black-towhite contrast. Moreover, by suitablyselecting the magnitude of the voltages V and V it is possible to freelyobtain an image in which the color of luminescence of the electricallyluminescent layer 14 is intensified or an image in which the color ofluminescence of the electrically luminescent layer l6 is intensified.

The above description has referred to a case in which the currents I and1 are in a differential relation and have the phases opposite to eachother, that is, a case in which the voltages V, and V are arranged tohave the phases substantially opposite to each other in consideration ofthe nature of the impedance of the layers including the impedance layer13, the highly resistive dielectric layer 18 and the high insulationlayer 17.

However, it will be understood that the anti-phase relation between thecurrents I and I hence V, and V is not an essential requirement, andtheir phase difference or their amplitude may be suitably varied asrequired to thereby control the colors of luminescence or theblack-to-white contrast or the gamma. In case there is a phasedifference of between the voltages V, and V the control of the colors ofluminescence can be most preferably attained by selecting the value of 6in such a way as to lie in a range (11/2) s 0 s (31r/2).

A further embodiment of the present invention with an associated powersupply system therefor is shown in FIG. 8.

The embodiment shown in FIG. 8 is generally similar to that shown inFIG. 6, but is different from the latter in that three spacedelectrically luminescent layers 14,

16 and 26 emitting the luminescence of three different colors, or morepreferably having the luminescence spectrum bands which may notappreciably overlap with each other, are disposed to lie in the gapportions of a plural-gapped electrode 15, and a dielectric layer 27 oftransparent and non-luminous nature is employed to fill the spacebetween the electrically luminescent layers 14, 16, 26 and to fill theremaining space in the gap portions of the plural-gapped electrode 15.Currents flowing from a planar electrode 12 and a pluralgapped electrode19 are concentrated to the pluralgapped electrode to establish a localhigh electric field around the plural-gapped electrode 15 so that theluminescence of the electrically luminescent layers 14,16 and 26 takesplace in a limited region substantially in the vicinity of theplural-gapped electrode 15.

It is also in the vicinity of the plural-gapped electrode 15 that thecurrent compensation described previously can be completely performed.Accordingly, the best characteristics can be obtained whenthe'electrically luminescent layers are confined to the neighborhood ofthe plural-gapped electrode 15. The disposition of the non-luminouslayer 27 between the electrically luminescent layers is effective forthe desired color separation or for the separation of the luminescencespectrum bands since the electrically luminescent layers emitting theluminescence of different colors are isolated from each other. Although,in FIG. 8, the electrically luminescent elements are shown as disposedin a limited area in the vicinity of each electrode element of theelectrode 15, these elements may be so disposed as to continuouslyextend between the adjacent electrode elements of the electrode 15.

The present invention disclosed herein provides an electricallyluminescent device which can very easily display a character or patterncompared with prior art devices of this kind, and can operate in a moreuseful manner than heretofore.

In the embodiments disclosed hereinabove, the case of applying a waterdroplet in such a manner as to conform with the shape of a character orpattern to be displayed has been described by way of example. It willhowever be understood that a substance having an impedance which islower than the electrical impedance of the layer portion lying in thegap portion of the plural-gapped electrode may be equally effectivelyused in place of water. Such substance is quite sufficient to serve asan electrode for the luminous display of a character or pattern depictedthereby. Therefore, when the material filling the gap portions betweenthe adjacent electrode elements of the plural-gapped electrode has ahigh resistivity, a substance having a resistivity sufficiently lowerthan the resistivity of the material may be used so that it can serve asan electrode for the luminous display of a character or pattern depictedthereby. Such substance may be a conductive paint prepared by suspendingpowders of metals such as silver in a ther-' mosetting resin such as anepoxy resin, a solution of an electrolyte, a water-soluble solution suchas an alcohol, or a liquid such as water having a low resistivity. Suchconductive paint or liquid, when used to depict a character or patternto be displayed on the layer including therein the plural-gappedelectrode, can sufficiently serve as an electrode for the luminousdisplay of the character or pattern. According to this method, anycomplex character or pattern can easily be depicted by a writing utensilsuch as a pen or brush. The character or pattern so depicted may easilybe erased by merely wiping away the conductive paint or liquid.

Further,,the conductive paint may be hardened and bonded to the surface,or the conductive powder mixed with an enamel frit may be coated on andbaked to the surface for the stable preservation of a character orpattern for a long period of time. Needless to say, an evaporated metalfilm may be deposited on the surface in lieu of the above bakingprocedure.

A solution prepared by dissolving a deliquescent substance such asmagnesium chloride into a volatile solution such as an alcohol or amixture thereof may 'be used to easily obtain an electrode of thedesired shape.

element which luminesces depending on the strength of an electric fieldapplied thereto, one of the electrodes being formed as a plural-gappedelectrode which serves as a power feeder for a conductive substancedisposed on the gap portion between the electrode elements so that suchsubstance can act as an electrode. It will be appreciated that theluminous display of a character or pattern can easily be effected bymerely depicting the character or pattern with the conductive substancein such a manner that the conductive substance electrically contacts atleast one of the electrode elements. It will further be appreciated thata plurality of portions isolated from each other can easily be madeluminant by merely applying the conductive substance to those portions,thus obviating the need for the provision of separate feeder wires.

We claim:

1. An electrically luminescent display device comprising twoelectrically luminescent films having different luminescent colors anddisposed adjacent to each other, first and second dielectric layersrespectively disposed on the opposite outer surfaces of the combinationof said electrically luminescent films, said second dielectric layerbeing light-permeable, a first electrode disposed on the outer surfaceof said first dielectric layer, a second electrode disposed on the outersurface of said second dielectric layer, a third electrode disposedbetween said two electrically luminescent films, said first-and thirdelectrodes being formed by a plurality of fine wires in a grid-likeconfiguration, means for applying a first voltage between said first andthird electrodes, means for applying a second voltage between saidsecond and third electrodes, and means for producing a pattern of visualcolor light emissions from said electrically luminescent filmscomprising a lowresistance material applied to preselected portions onsaid outer surface of said first dielectric layer, said lowresistancematerial being in electrical contact with adjacent portions of saidelectrode.

2. An electrically luminescent display device according to claim 1,further comprising a third dielectric layer, separate from said firstdielectric layer, disposed between said first dielectric layer and saidcombination of electrically luminescent films.

3. An electrically luminescent display device, comprising: a firstdielectric layer; an electrically luminescent film comprising first,second and third layers disposed within said first dielectric layer andspaced apart from each other by said first dielectric layer; a firstelectrode having a grid-like configuration, wherein said first, secondand third electrically luminescent layers are disposed within the gapsin said first grid-like electrode; second and third dielectric layersdisposed on opposite sides of said electrically luminescent film; secondand third electrodes disposed on the outer surfaces of said second andthird dielectric layers, respectively, and spaced from said electricallyluminescent film by said respective second and third dielectric layers;and means applying a first voltage between said first and secondelectrodes and means applying a second voltage between said first andthird electrodes.

4. An electrically luminescent display device according to claim 3,further comprising a fourth dielectric layer, distinct from said thirddielectric layer, disposed between said third dielectric layer and saidelectrically luminescent film.

5. An electrically luminescent display device according to claim 3,wherein said first, second and third electrically luminescent layershave different luminescent spectrum bands.

6. An electrically luminescent display device, comprising: anelectrically luminescent film; first and second second planer electrodesdisposed on opposite sides of said electrically luminescent film, atleast one of said electrodes being formed of a plurality of wires in agrid-like configuration; a dielectric layer disposed between saidgrid-like electrode and said electrically luminescent film; and aconductive substance having a resistivity lower than that of saidphosphor layer and placed on said dielectric layer in the shape ofcharacteristics or patterns to be displayed, the gridlike electrodeserving as a feeder wire for said conductive substance.

7. An electrically luminescent display device according to claim 6,further comprising: a second dielectric layer, separate from thefirst-mentioned dielectric layer, disposed between and adjacent saidfirstmentioned dielectric layer and said electrically luminescent film.

1. An electrically luminescent display device comprising twoelectrically luminescent films having different luminescent colors anddisposed adjacent to each other, first and second dielectric layersrespectively disposed on the opposite outer surfaces of the combinationof said electrically luminescent films, said second dielectric layerbeing light-permeable, a first electrode disposed on the outer surfaceof said first dielectric layer, a second electrode disposed on the outersurface of said second dielectric layer, a third electrode disposedbetween said two electrically luminescent films, said first and thirdelectrodes being formed by a plurality of fine wires in a grid-likeconfiguration, means for applying a first voltage between said first andthird electrodes, means for applying a second voltage between saidsecond and third electrodes, and means for producing a pattern of visualcolor light emissions from said electrically luminescent filmscomprising a low-resistance material applied to preselected portions onsaid outer surface of said first dielectric layer, said low-resistancematerial beIng in electrical contact with adjacent portions of saidelectrode.
 2. An electrically luminescent display device according toclaim 1, further comprising a third dielectric layer, separate from saidfirst dielectric layer, disposed between said first dielectric layer andsaid combination of electrically luminescent films.
 3. An electricallyluminescent display device, comprising: a first dielectric layer; anelectrically luminescent film comprising first, second and third layersdisposed within said first dielectric layer and spaced apart from eachother by said first dielectric layer; a first electrode having agrid-like configuration, wherein said first, second and thirdelectrically luminescent layers are disposed within the gaps in saidfirst grid-like electrode; second and third dielectric layers disposedon opposite sides of said electrically luminescent film; second andthird electrodes disposed on the outer surfaces of said second and thirddielectric layers, respectively, and spaced from said electricallyluminescent film by said respective second and third dielectric layers;and means applying a first voltage between said first and secondelectrodes and means applying a second voltage between said first andthird electrodes.
 4. An electrically luminescent display deviceaccording to claim 3, further comprising a fourth dielectric layer,distinct from said third dielectric layer, disposed between said thirddielectric layer and said electrically luminescent film.
 5. Anelectrically luminescent display device according to claim 3, whereinsaid first, second and third electrically luminescent layers havedifferent luminescent spectrum bands.
 6. An electrically luminescentdisplay device, comprising: an electrically luminescent film; first andsecond second planer electrodes disposed on opposite sides of saidelectrically luminescent film, at least one of said electrodes beingformed of a plurality of wires in a grid-like configuration; adielectric layer disposed between said grid-like electrode and saidelectrically luminescent film; and a conductive substance having aresistivity lower than that of said phosphor layer and placed on saiddielectric layer in the shape of characteristics or patterns to bedisplayed, the gridlike electrode serving as a feeder wire for saidconductive substance.
 7. An electrically luminescent display deviceaccording to claim 6, further comprising: a second dielectric layer,separate from the first-mentioned dielectric layer, disposed between andadjacent said first-mentioned dielectric layer and said electricallyluminescent film.